Fig. 3: Proposed self-limiting climb and drive growth mechanism of the TMD nanograin films.
From: Engineering grain boundaries at the 2D limit for the hydrogen evolution reaction
a Schematic of the climb stage: the Au QDs droplets tend to climb onto the MoS2 monolayer from the SiO2 substrate due to the surface tension difference. b Schematic of the drive stage: the growth of a second MoS2 layer tends to push the Au QDs along the growth direction. Most of the Au QDs will be stabilized at the grain boundaries in order to minimize their surface energy. c SEM image showing the distribution of the Au QDs on the edges of growing MoS2 layers (marked by the red-dashed line). Au QDs are usually larger on the MoS2 layers (indicated by blue arrows) than those observed on the SiO2 substrate. d Real-time phase-field simulation showing the formation of the MoS2 nanograin film. The Au QDs numbered 1–4 show that the growth of the MoS2 layer will push Au QDs toward the grain boundaries. Au QDs numbered 5–6 show a zipper effect to suture the neighboring grains together. The movie can be found in Supplementary Movie 1 (Real-time phase-field simulation of the growth process).
